sturgis



March 8,1932 w. B. STURGIS I AUTOMATIC-DRAFT REGULAIOR Filed March 11, 1929 Patented Mar. 8, 1932 UNITED STATES PATENT OFFlCE WILLIAM B. STUBGIS, OF CHICAGO, ILLINOIS AUTOMATIC nm'r REGUIATOB Application filed larch 11, 1929. Serial No. 848,114.

The present invention relates generally to automatic draft regulating devices for maintaining a uniform or constant draft in the flue or outlet conduit of a heating apparatus by automatically regulating the entry of air into such flue in response .to' variations or fluctuations in the pressure of the escaping gases and products of combustion. More particularly the invention relates to that type of draft regulating device that embodies a counterbalanced damper plate or valve which is positioned adjacent to one end of a horizontally extending air inletpipe and ismounted to swin on a fixed horizontal axis which is dispose eccentrically with respect to the damper plate'and the air inlet pipe.

In regulator or damper devices of this character, the plate or valve is caused to be 0 sition whenever the upward flow of gases andswung or tilted from its closed or vertical poproducts of combustion through the flue to the chimney creates in'the air inlet pipe a suflicient suction or partial vacuum to overcome the action of the counterweight. This is attributable to the fact that one of the two parts of the damper plate atopposite sides of the axis of rotation is of greater area than the other part, and consequently responds to the differential pressures that exist inside and outside the inlet pipe. As the plate swings towards its fully opened or horizontal position, it is manifest that the active or suction responsiveportion of the plate, that is,

the portion that is in the larger of the two parts and is responsible for the tilting or valve opening action, gradually decreases in effective area. To cause the effective weight of the counterweight to diminish correspondingly in direct ratio or proportion to the suction responsive portion of the plate for the .purpose of effecting and maintaining a uniform draft in the flue, it has heretofore been proposed to locate the counterweight on the distal end of a fixedly mounted rod which projects from one face of the plate and at right angles to the plane of the plate and is positioned in substantially intersecting relation with the axis of rotation. Whereas a counterweight arrangement of this character results in the damper plate operating efiitensities is exceedingly small and it is practically impossible to adjust the counter weight so that the plate is extraordinarly sensitive and is capable of being set to refslpond to minimum draft intensities in the One object-of this invention is to improve upon dampers of the type. and arrangement previously referred to b providing counterbalancing means. where y the range within which the damper plate may be adjusted for diflerent draft intensities is materially increased and the damper plate'is capable of being set or adjusted to maintain a minimum uniform draft in the flue. In general this counterbalancing means comprises a rod which extends through the axis of rotation and at right angles to the plane of the damper plate; so that the eflective weight thereof diminishes proportionately or corresponding- 1y to the suction responsive portion of the damper plate'during opening of the latter, and which projects outwardly from both faces of the plate and is mounted in place so that it may be shifted longitudinally in either direction for draft adjustment purposes. By shifting the rod bodily in one direction or the other, it is possible to counterweight variably the damper plate so that the latter operates to effect in the flue a uniform draft of substantially an desired intensity.

Another 0 ject of the inventon is the provision of'weights on the ends of the rod, which are individually movable lengthwise of the rod to effect a secondary adjustment of the counterweight means.

A further object of the invention is to provide an automatic draft regulator or damper to provide an improved damper which may be manufacturedat a comparatively low costand operates efliciently to maintain a constant or a uniform draft in the flue.

In addition, it is contemplated as one of the objects of the invention to provide an automatic draft regulator device which is an improvement upon that disclosed in Letters Patent of the United States No. 1,787,738, granted to me January 6, 1931.

Other objects of the invention and the various characteristics and advantages of the present construction will be apparent from a consideration of the following detaileddescri tion.

he invention consists in the several novel features hereinafter set forth and more particularl defined by the claims at the conclusion hereof In the drawings which accompany and form a part of this specification or disclosure and in which like numerals of reference denote corresponding parts throughout the several views:

Figure 1 is a vertical sectional view'of a damper or automatic draft regulator embodying the invention, the damper plate or valve being shown in its vertical position, that is, the position that it assumes when not affected by a partial vacuum in the air inlet pipe;

Figure 2 is a front view;

Figure 3 is a perspective of the damper plate, illustrating in detail the pivot shaft and the balancing and counterbalancing means; and Y Figure 4 is a detail sectional view of the collar which connects the rod .and counterweights to the pivot shaft.

The device which forms the subject of the invention. is o erative to maintain auto-- matically a uni orm draft in the flue 10 of a heating'apparatus, such, for example, as a furnace or heater fired by an oil burner. The flue 10 is adapted to conve upwardly the various gases and products 0 combustion and extends between the as outlet for' the comhustion chamber an the chimney of the building with which the "heating apparatus is associated. -A horizontallyextending air inlet pipe 11 is connected to one side of the flue 10.and is adapted to permit air to enter the interior of the fluetodecrease the draft. In the drawing, the flue 10 and air inlet pipe 11 are shown in the nature of a T-shaped'pipe section. The improved draft regulating device is adapted to control the passage of air through the inlet pipe 11 so as to maintain a substantially uniform draft in the flue 10. It comprises a cylindrical sheet metal pipe section 12, one end of which fits within the pipe 11. The said one end of the pipe section 12 is preferably crimped, as indicated in Figure 1.

of the drawings, to permit it to be shifted readily into frictional engagement and sealed relation with the pipe 11. An annular head 13 is formed adjacentto the central portion of the pipe section 12 and forms a stop which operates to prevent the pipe section from being shifted too far into the pipe 11. The outer end of the pipe section is rolled or deflected backwardl'y around a wire hoop 14 for reenforcing purposes and to eliminate any exposed edges. The automatic draft regulating device, in addition to the pipe section 12, comprises a valve or damper plate 15 which is of circular conformation and such size as to close the passageway or conduit in said pipe section 12. This damper plate is preferably formed of sheet metal and has the marginal portion thereof bent inwardly to form a. circumferentially continuous annular flange 16. A horizontal shaft 17 operates to form a pivotal support for the plate 15. The central portion of the shaft is soldered or otherwise rigidly secured to the inner face of the damper plate and the ends thereof project through circular apertures 18 in the. flange 16 and are journalled in oppositely facing holes 19 in the side portions of the pipe section 12. Spacing Washers are mounted on the shaft 17 between the annular flange 16 and the portions of the pipe section 12 that form the holes 19. The shaft 17 is positioned beneath the center of the damper late and the axis of the pipe section 12. y positioning the shaft in this manner, the damper plate embodies more area or surface in the portion thereof above the pivot shaft than in the lower portion, and consequently is tilted into an angular position when unequal pressures exist inside and outside the pipe 12, that is, whenever the draft in the flue 10 creates a partial vacuum in the air inlet pipe 11.

' A weight-member 20 is secured by a bolt 21 to the lower portion of the damper plate 15. This member embodies a depending offset portion 22 which cooperateswith the bottom part of the portion of the pipe section 12 that is rolled around the wire hoop 14, to limit the tilting movement of the damper plate and prevent the latter'from being swung outwardly in the event back pressure occurs in the flue 10 which sometimes takes place when the heating apparatus is not in ,use. The member 20 tends, in conjunction with the counterbalancing means hereinafter described, to maintain the damper plate in its closed or vertical position. To prevent the damper plate from being shifted into a horizontal position, in which'position the plate, if approximately balanced, would not return to its closed position, a stop 23 is provided.

This stop is in the nature of a bolt which extends through one side of'the pipe section 12 and is located slightly above the axis of ro-- tation, as indicated in Figure 1.

The plate is counterbalanced by means of I a rod 24. This rod is mounted in a collar 25 which is rigidly secured to one end of'the pivot shaft 17 by a set screw 26. The rod 24.

. is arranged to extend at right angles to the plane of the damper plate so that the effective weight thereof decreases in direct ratio or proportionally to the effective suc- -tion responsive area of the upper portion of the damper plate during opening. of the latter. The collar 25 and the rod are connected together by a screw thread connection 27 which consists of a male thread on the rod and a female thread in the collar. By means of this screw thread connection, it is possible by rotating the rod, to shift the latter longitudinally or axially to effect the desired application of the counterweight. A characteristic and an advantage of the counterweight means set forth is that the range tive to light currents of air passing through the air inlet pipe and consequently operates to effect in the flue 10 a uniform draft of minimum intensity. When the rod '24 is shifted outwardly with respect to the damper plate as far as possible, the effective weight thereof tends to increase the resistance of the damper plate to the flow of air through the pipe 11 and consequently the draft main tained within the flue 10 is of a materially greater intensity; v

To permit of a minute or secondary adjustment of the counterweight means, a pair of weights 28 and 29 are provided. These weights are mounted on the ends of the rod 24 and have female screw threads formed therein, which cooperate with the male thread I on the rod to enable the weights to be shifted longitudinally for adjustment purposes. By manipulating or shifting longitudinally the rod 24, it is possible to cause the damper plate to effect approximately in the flue 10, a uniform draft of a desired intensity. By

' rotating either of the weights 28 and,29, a

secondary and more minute adjustment is obtained and it is possible to effect the exact. desired draft intensity in the flue. The rod 24, together with the weights 28 and 29, ex-

emplify counterbalancing means of an improved character.

In practice, it has been found that a more uniform and constant draft is obtained when the damper plate 15 is made to balance approximately, prior to the securing in place of the rod 24 and the weights 28 and 29. With this in view, the-end of the shaft 17, opposite the collar 25, is bent downwardly to formanelement 30 which extendstransversely to the axis of rotation and lies in the plane of the damper-plate. A weight 32.is connected to the element 30 by a screwthread connection 31 so that it may be adjusted to and-from the shaft 17: By adjusting the position of the weight 32, it is possible to have the damper plate properly balanced prior to the application or assemblage of the counterbalancing means. If the weight-member 20 proves not to be heavy enough to balance the plate properly, the counterweight 32 is adjusted downwardly until the desired balance is obtained. In addition to the function heretofore specified, the weight 32 and the element 3() permit of a ready adjustment in the event the use of a draft gauge discloses that the member 20 is not of the proper weight to effect the maintenance of. a draft of uniform intensity. If a draft gauge shows that the draft in the flue 10 is not substantially .uniform under all conditions, the weight 32 may be adjusted without the dismantlement of the regulator device proper until the desired draft uniformity is obtained.

When the automatic draft regulator is installed, the counterbalancing means is removed or disconnected with respect to the collar 25 so that the operative or individual effecting the installation may cause the damper plate 15 to be properly balanced by adjustment of the weight 32 relatively to the element 30. After the plate has been pro erly balanced, the pipe section 12 is shi ted into its operative position with its crimped end in frictional engagement with the air inlet pipe 11. The rod 24 is then screwed through the 'collar 25, and the weights 28 and 29 applied to the ends thereof. To adjust the device for the desired draft intensity, the rod 24 is shifted long1-' udinally until approximately the proper counterbalancing of the damper plate is effected. The weights 28 and 29 are then manipulated to effect a final or secondary ad-. justment and to cause the damper plate to maintain in the flue 10 a uniform draft of v tity of air into the pipe 11. This additional supply of incoming air reduces the draft to ficient in operation due to the specific counterbalancing means explained, which means permits the damper plate to be adjusted for different uniform draft intensities within a large range.

The inventionis not to be understood as restricted to the details set forth, since these may be modified within the scope of the appended claims, without departing from the spirit and scope of the invention.

. Having thus described the invention, what I claim as new and desire to secure by Letters Patent, is:

1. A damper device for automatically maintaining a uniform or constant draft of a desired intensity in a flue,'the combination of a casing having a passageway therethrough for introducing air into the flue, a plate for controlling the flow of air through the casing and into the flue, means forming a support whereby the plate is pivoted eccentrically so as to swing on an axls in the plane of the plate, means for accurately balancing the plate about its axis of rotation comprising a weight-element mountedso that it is movable bodily in the plane of the plate towards and away from the axis of rotation, andadjustable counterbalancing means for the late comprising an elongated arm extendmg through the axis of rotation and projecting outwardlyrelatively to both faces of the plate, said arm bei. mounted in place so that it may be shiftef longitudinally for counterbalancing purposes and being arranged so that it extends horizontally when the plate is in its closed position in order that the leverage thereof upon the plate decreases constantly as the damper opens.

2. In a damper device for automatically maintaining a uniform or constant draft of a desired intensity in a flue, the combination of a casing having a passageway therethrough for introducing air, into the flue, a plate for controlling the flow of air through the casing and into the flue, means forming a support whereby the plate is pivoted eccentrically so as to swing on an axis in the plane of the plate, means for accurately balancing the plateabout its axis of rotation comprising a weight-element mounted so that it is movable bodily in the plane of said plate towards and away from the axis of rotation,

it is movable bodil and adjustable counterbalancing means for the plate comprising an arm pro ecting radially with respect to the axis of rotation of the plate and a weight-element mounted on the arm so that it is movable bodily towards and away from the axis of rotation for counterbalancin purposes, said arm being arranged so t at it extends horizontally when the plate is in its closed osition in order'that. the combined leverage o the arm and the last mentioned weight-element upon the plate decreases constantly as the damper opens.

3. In a damper device for automatically maintaining a uniform or constant draft of a desired intensity in a flue, the combination of a casing having a passageway therethrough for introducing air into the flue, a plate for controlling the flow of air through the casing and into the flue, means forming a support whereby the plate is pivoted eccentrically so as to swing on an axis in the plane of the plate, means for accurately balancing the plate about its axis of rotation comprising an arm disposed in the plane of the plate, and a weight-element mounted on the arm so that it is movable bodily in the plane of the plate to and from the axis of rotation, and adjustable counterbalancing means for the plate comprising an arm projecting radially with respect to the axis of rotation of the plate and a weight-element mounted on the arm so that it is movable bodily towards and away from the axis of rotation for counterbalancing purposes, said counterbalancing arm being arranged so that it extends horizontally when the plate is inits closed position in order that the combined leverage of the counterbalancing arm and the last 7 mentioned weight-element upon the plate decreases constantly as the damper opens.

4. In a damper device for automatically maintaining a uniform or constant draft of a desired intensity in a flue, the combination of a casing having a horizontal passageway therethrough for introducing air into the flue, a plate for controlling the flow ofair throu h the casing and into the flue, said plateeing pivoted beneath its center so as to swing on a horizontal axis and being adapted when in its vertical position, to close completely the passageway, means for accurately balancing the plate about its axis of rotation comprising an arm extending downwardly from the axis of rotation and disposed in the plane of the plate, and a weightelement mounted on the arm so that it is 'movable bodily in the plane of the plate to ,prising an arm projecting radially with respect to the axis of rotation of the plate and a weight-element mounted on the arm so that towards and awa from the axis of rotation for counterba ancing purposes, said counterbalancing arm extending at right angles to the plate so that it is truly horizontal when the plate is in its closed position and the combined leverage of the counterbalancing arm and the second mentioned Weight-element decreases constantly as the plate swings into its open position.

5. In a damper device for automatically maintaining a uniform or constant draft of a desired intensity in a flue, the combination of a pipe section for introducing air into the flue, a plate for controlling the flow of air through the passageway into said flue, a

shaft connected fixedly to the plate and forming a pivotal support whereby the plate is pivoted eccentrically and so was to swing on an axis that is substantially in the plane of the plate, means for accurately balancing the plate about its axis of rotation, comprising an elongated member connected to one end of the shaft and projecting laterally therefrom in the plane of-the' plate and a weight mounted on and movable longitudinally of the arm, and adjustable means for counterbalancing the plate comprising an elongated member projecting laterally from the other endof the shaft and extending at right angles to the plane of the plate and a weight mounted on and movable longitudinally of the member.

Signed at Chicago, Illinois, this 9th day of March, 1929.

WILLIAM B. STURGIS. 

